Intense ultrasonic fields are used for treating materials in various ways including cleaning surfaces, promoting certain types of chemical reactions, and degassing liquids. Such fields are generally generated by electrically driven piezoelectric or magnetostrictive transducers.
McCord, U.S. Pat. No. 4,618,263 discloses an acoustic cleaner which incorporates a cavitation generator for agitating liquid in an enclosure. The enclosure is provided with a wave reflecting surface for reflecting acoustic waves from the margin of the liquid back into the body of the liquid to reinforce cavitation in the chamber.
Kanazawa, U.S. Pat. No. 4,727,734 discloses an ultrasonic clothes washer. The washer has a metal tub for receiving clothes. Bubbles are introduced into the tub to promote cavitation and to reflect the ultrasound so that all articles in the tub are irradiated with ultrasound.
Prior art cavitation chambers suffer from the disadvantage that it is difficult to efficiently transmit energy from the vibrating face of the transducer into a liquid in a cavitation chamber as acoustic vibrations. Some prior art cavitation chambers attempt to solve this coupling problem by providing the cavitation chamber with walls designed to resonate at the frequency of the transducer. A further disadvantage of prior art cavitation chambers is that the electromechanical equipment for generating high powered acoustic signals with a piezoelectric or magnetostrictive transducer is inherently expensive and inefficient.